Thread-trimming device for sewing machines



Dec. 8, 1925- 1,565,159 J. KIEWICZ THREAD TRIMMING DEVICE FOR SEWING MACHINES Filed Feb. 26, 1921 3 Sheets-Sheet 1 Fig.1.

I lrivenTor. John Kiewicg Aflys.

Dec. 8, 1925 1.565.159

- J. KIEWICZ THREAD TRIMMING DEVICE FOR SEWING MACHINES Filed Feb. 26, 3921 3 Sheets-Sheet 2 Fig.2.

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J. KIEWICZ THREAD TRIMMING DEVICE FOR SEWING MACHINES Filed Feb. 26. 1921 3 Sheets-Sheet 3 lnvenTor. John Ki ewic by/kwwaw AITys.

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JOHN KIE'WICZ, 015 BOSTON, MASSACHUSETTS, ASbZGNUl-t TO THE REESE BUTTONHOLE MACHINE OOIJJIPANY, 0F BOSTOH, TJIASSAGI-IUSET'ES, A CGIRPORATIDN OF MAINE.

THBEAD-TEIIVIIJJIING DEVICE FGR SEW'ING MACHINES.

Application filed February 26, 1921.

T0 Md whom it may concern:

lie it known that 1, JOHN Kinwroz, acitizen. of the United States, resident of Boston, county of Suffolk, State of Massachusetts, have invented an Improvement in Thread- 'lrimming Devices for Sewing Machines, of which the following description, in connection with the accompanying drawing, is a specification, like characters on the drawing representing like parts.

This invention relates to thread trimming devices for sewing machines of that type which are constructed to sew a short seam and then automatically come to rest (such tor instance as buttonhole sewing machines), and said invention relates particularly to that class of thread trimming devices which is constructed to cut the needle thread close to the work at the end of each sewing operation and hold the cut end until after the :lirst few stitches of the next succeeding sewing operation have been taken and then to cut the end of the thread thus held. This type of thread cutting device will therefore out the thread twice during each sewing operation, once after the first few stitches have been formed at the beginning of the sewing operation and again after the sewing operation has been completed.

Buttonhole sewing machines are usually provided with stitch-forming mechanism and with work-holding means arranged to have a relative movement during the stitchon a buttonhole and some buttonhole sewing machines are constructed so that the stitch-forming mechanism and work-holding means have an additional relative movement just before the stitching operation begins and just after said stitching operation ends, such additional relative movement being for the purpose of carrying the parts from buttonhole-cutting position to stitching position and vice versa. These buttonhole sewing machines are usually arranged so that when the machine comes to rest at the end of the stitching operation the stitching mechanism and work-holding means are relatively in lmttonhole-cutting position.

in some machines the cutting of the but tonhole is accomplished before the stitching is done on the buttonhole, while in other Serial No. 447,988.

machines the buttonhole is out after the stitching is completed. In either case, however, when the sewing machine is started the work is first clamped in the work-holding means, the work then being in buttonholecutting position, and if the machine is of the type wherein the buttonhole is out before the stitching operation, then the buttonhole cutter operates to cut the buttonhole, after which the stitch-formh1g mechanism and work-holding means have a relative movement to bring the parts into stitching position, or in other words, to bring the work and needle into such relative positions that the stitching may be properly done on the buttonhole. At this time the stitch-forming mechanism is set in operation to form the stitches around the buttonhole and during this operation the work holding means and stitch-forming mechanism have a relative feeding movement. When the stitching on the buttonhole is completed the stitch-forming mechanism comes to rest and then the worleholding means and stitch-forming mechanism have a further relative movement to bring them relatively into lnittonhole-cutting position, in which position the machine comes entirely to rest. If the sewing machine is of the type in which the buttonhole is out after the stitching operation, then the buttonhole cutter will be operated to cut the buttonhole after the parts are relatively in buttonhole-cutting position but before the machine comes entirely to rest.

It is one of the objects of my present invention to provide a thread-trimming mechanism of the type above referred to, that is, one which cuts the needle thread twice, once at the beginning and again at the end of each buttonhole, and which is actuated to perform its two thread cutting operations by the relative movement between the stitchforming mechanism and work-holding means.

With my invention the cutting of the thread at the end of the buttonhole is accomplished through the relative movement of the work-holding means and stitch-forming mechanism by which the parts are carried from stitching position to buttonholeginning oi the buttonhole is accomplished by the relative feeding movement between these parts.

In some buttonhole sewing machines the relative movement between the stitch-forming mechanism and work-holding means is secured by moving the stitch-forming mechanism and in other sewing machines it is secured by moving the work-holding means. I have herein chosen to illustrate my invention as it would be embodied in a sewing machine in which the stitch-forming mechanism moves to secure the above-described relative movement but I do not wish to be limited to sewing machine having this particular feature.

In order to give an understanding of my invention 1 have illustrated in the drawings a selected embodiment thereof which will now be described after which the novel teatnres will be pointed out in the appended claims.

Fig. l is a side view of a portion of a buttonhole sewing machine having my improve ments applied thereto.

2, 3 and show plan views of the thrcad-trimming device, saio figures showing the position oi the parts at different stages in the formation of the bntto' .hole.

Figs. 5 and are views illustrating the operation of the switch cam which controls the movement of the thread gripping member.

Fig. 7 is a sectional detail view showing the finger 32.

Fig. 8 is a section on the line 88, Fig 8.

In the sewin machine shown in the drawings the stitch-forming mechanism comprises :zn upper needle tor manipulating the upper needle thr ad 5 and an under thread manipulating mechanism (not shown) carried by a turret situated beneath the bed 1, the needle 1 being carried by the usual needle bar 3 which reciprocates in the head 2. The work-holding means is supported on the bed i. and comprises the usual clamp plates (3 and w s. clamps i which are pivoted to ti o clamp ,lates at 8 and are constructed to clamp he work against the clamp niates.

The bnttonhole cutter is shown at 9 itnd is carried by a swingi arm l0 usual in sewing machines of this type. in the sewing ma hine herein shown the head 2 is incnntcd to more back and forth on the bed 1 thereby to provide for the relative move ment between sch-forming mechanism neans above referred to 1 is secnred through the i as:

opera n oi a ma or ieed cam (not shown) operating benea the bed 1. Examples of buttonhole sew machines of this type may is found in United States Patents No. it, T, 1300 No. 862,238, Aug. 6,

i907, to which referen e may be had for a more ,-on:1pletc description of the means for operatic. g the stitch-forming mechanisn'i for moving the head 2 relative to the wow-:-

ding means.

Tihen the machine has been brought to over tl worl: clamp "I and in position to l mttonhole in the work "U7 when it is r the work clamp T. in this posi- Q i will he sitnatcd in front ti tonnolc. Then the machine is t. and after the work clamps have red the work then the head is given ent to the right, Fig. l before the stitch-forming i'nechanism is set in operation thereby to arry the needle into the dotted line position Fig l, or in position to commence the stitching on the bnttonhole the buttonholc cutter this movement being carried back out of the way. it this time the stitch-forming mechanism is set in operation. it being driven from the shaft 11 and the stitching is performed down one s ide of the bnttonhole, around the eye of the huttonhole, and then back along the other side of the buttonhole and during this operation the head 2 will have a feeding movement first in one direction and then in the other. li hen the stitching on the bu tonhole is completed the needle will be in the dotted line position l ig. and before the machine comes to rest the head 2 is given a further movement to the left into 1 full line position Jig. l. i i hilc this icratixn is common to buttonholc sewing achines (it this type, yet i have thought it wise to rehearse it here as it would be a help in understanding the operation oil? my IOU cutter in retracted position and w c. extension oi the arm 13 against the stop 18.

.Lssociatcd with the thread cutte' is a thread-holdirig device which comprises a My sta ioi'iary clamping member if) that is s cured to the arm of the work clamp and movable clamping member 20 carried by an arn'i 2i and pivz, ed at to th arm 15 of the work clamps. The clamping men'ihe 20 h ol: 9 i 'i id it flli. i i is Ox Jmpet :11 L i cs in plate 19 and is; provided with a depend flange 28 adapted to engage the edge of the pie. e 19 as shown in Fig. 8. The arm 21 carrying the thread clamping member 20 is W) acted upon by a spring 24 which normaiy tends to maintain it in the positions shown in Figs. 2 and 8 The cutter 12 is situated directly beneath the plate 19 and the cutting edge 25 thereof operates to shear the thread directly beneath the plate 19 and the flange 23, as will be ol vious from Fig. 8. The thread gripping device is arranged to grip the needle thread at the end of each sewing operation so that when the machine comes to rest the end of the needle thread is held by the gripper as shown in Fig. 1.

As stated above the cutter 12 makes one cutting movement at the end of the stitching on a buttonhole and a second cutting movement at the beginning of the stitching at the next succeeding buttonhole and this is herein accomplished by forming the extension 1'? or" the arm 13 with the curved por- I tion 215 that provides the two cam surfaces 27, 2S and by also providing the head 2 with a l'lange or arm 29 which engages these cam surfaces as the head moves back and forth during the cycle of operations.

Fig. 2 illustrates the position of the parts when the machine is brought to rest and the buttonhole has been cut and at this time the head 2 is in its forward position and the arm 29 engages the extension 17, as shown in Fig. 2, thereby holding the cutter in its forward position. At this time the needle occupies approximately the position indicatcd in Fig. 2 and the needle thread extends from the needle to the gripper shown in Fig.

' 1. When the sewing machine is started in operation the head 2 is first moved from buttonhole cutting position, shown in Fig. 1. into stitching position thereby to bring the needle into the dotted line position, Fig. 1, and into the position shown in Fig. 3. At this time the needle is in position to com mence the stitching on the buttonhole and the end of the needle thread is still held by the gripper. The movement from stitching to buttonhole-cutting position is suificient to carry the arm 29 into the curved portion 26 between the cam surfaces 27 and 28 as shown in Fig. 3. At this time the spring 16 acts to retract the cutter into the position shown in Fig. 21. The shaft 11 is now set in opera tion to start the stitch-forming inechani and the head 2 has a slow feeding moveine to the right. Fig. 1, to carry the stitching down one side oi the buttonhole and during this movement the arm 29 engages the can snrtace 28 thereby swinging the cutter "for; wardly into the dotted line position Fig. 3, this operation causing the cutter to cut the end of the thread which is held by the grip- As the stitching around the buttonholo continues the head 2 will move to its limit to the right, 1 and then move to.

the left again in Fig. 1 until. it arrives at the dotted l no position. which is the posiiacn it assumes when the stitching on the buttonhole is completed. At this time the arm 29 has again come into the position shown in Fig. 3 and when the head has its linal movement from stitching to buttonhole cutting position or from the dotted line position ig. 1 to the full line position the arm will engage the cam surface 27, thereby causing the cutter to out the thread between the needle and the work.

The thread gripping device is actuated by a pin or projection 30 carried by the head 2. The arm 21 oi the gripper has an extension 31 on which is pivotaily mounted a finger 32 that is provided at its lower end with a shoe 33 having the cam surfaces 3 1, The linger 32 is acted upon by a spring 36 which normally holds it against a stop finger 37 carried by a collar 38 that is fast to the exten sion 31. lhis stop finger 3T limits the swing ing inoven'ient of the mger 32 in one direction but said linger is free to swing in the opposite direction. Since the pin 30 is car ricd by the heat 2 it moves back and forth with the head and said pin is so positioned that just before the stitching on a buttonhole has been completed, said pin will engage the cam surface 31- ot the shoe and by acting thereagaiust will swing the lever 21 from the position shown in Fig. 2 to that shown in Fig. lVhile the pin 30 is engaging the cam surface 3 1 the linger 32 is held a ainst the stop 37 and therefore the action or the linger against the cam swings the arm 21 as above stated. This movement of the arm 21 carries the gripping member 20 across the line of stitching to the opposite side of the needle thread and the gripper 20 is maintained in this position until the head has moved forward sufficiently to carry the pin 30 past the shoe 33. ii hen the pin has moved past the shoe 33 then the spring 2st operates to return the gripper into its operative gripping position shown in Figs. 2 and 3. The parts are so timed that before the pin leaves the shoe 33 the portion of the needle thread extending from the work to the needle will lie between the hooked portion of the gripper 20 and the gripping member 19 so that when the pin 30 is carried past the shoe the movement of the gripping member from the position shown in Fig. 4- to that shown in Figs. 2 and 3 will cause the needle thread to be gripped between the flange 23 and the gripping member 19 as shown in Fig. 8. This occurs after the stitch-forming mechanism has come to rest and before the cutter 12 has its thread-cutting movementat the end of the stitching operation. Hence when the cutter operates to cut the thread at the end of the stitching operation the thread is held by the gripper and as the cutter operates between the gripper and the worl: end of the needle thread will be retained in the gripper.

When the machine is started in operation again and the head moves from buttonholecutting position to stitching position the pin 30 again engages the shoe 33 but at this time it engages the cam surface 3:") as shown in Fig. and because therarn'i 32 is pivotally mounted on the extension ill the shoe at this time is merely swung laterally away from the stop 37 and gives no movement to the thread-gripping member 20. The thread gripper therefore is only operated at the end of the buttonhole when it is necessary to grip the needle thread. On the other hand the thread cutter is actuated twice, once at the beginning of the stitching operation and again at the end of the stitching operation.

I claim:

1. In a sewing machine constructed to sew a short seam and then come to rest, the combination with stitch-forming mechanism and work-holding means movable relatively to each other, said stitch-forming ine hanisu including a needle, of means operative at the end of each seam to grip the needle thread between the needle and the work,

means to cut the thread between. the gripper and the work, and means rendered operative by such relative movement to actuate first the thread gripping device at the end of each seam, then to actuate the cutter to cut the thread, and also to actuate the cutter a second time after the next succeeding seam has begun to be stitched.

2. In a sewing machine constructed to sew a succession of short seams and to come to rest at the end of each seam, the combination with stitch-forming mechanism and work-holding means movable relatively to each other, of means adapted to take and hold the needle thread between the needle and the work, a cutter having a cutting edge adapted to sever the thread between the holding means and work, and means rendered operative by such relative movement to cause the thread-holding means to take the needle thread after the completion of one seam and to hold it While the thread is severed and while a second seam is there after begun to be stitched, and also to cause the said cutting edge to cut the thread both at the end of each seam and after the starting of the stitching on the next seam.

3. In a sewing machine, the combination with work-holding means and stitch-forming mechanism having relative movement, of a thread holder, a movable thread utter, means operated by said relative movement to cause the thread holder to grip the thread at the end of the seam and to give the thread cutter a thread-cutting movement both at the end of the seam and at the beginning of the seam.

4. In a buttonhole sewing machine, the combination with Work-holding means, of stitch-forming mechanism movable relative to the worlcholding means while the edge stitches are being formed on a buttonhole and having a further relative movement to carry the parts from stitching position to buttonhole-cutting iosition and vice versa, a thread-gripping device, a thread-trimming device, and means actuated by the relative movement of the stitch-forming mechanism to cause the thread-gripping device to grip the needle thread at the end of each buttonhole and to cause the thread-trimming device to trim the thread after ithas been thus gripped and again after the stitching has con'nnenced on the next huttonhole.

In a buttonliole sewing machine, the combination with work-holding means, of stitch-forming mechanism movable relative to the work-holding means while the edge stitches are being formed on a buttonhole and having a further relative movement to carry the parts from stitching position to liuttonhole-cutting position and vice versa. a thread-gripping device, a thread-trimming device, means actuated by the movement of the stitclrforuiiug mechanisn'i from stitching position to buttonhole-cutting position at the end of each buttonhole to cause the thread-gripping device to grip the needle thread and the trimming device to trim said thread and bythe feeding movement of the stitch-forming mechanism when the stitching on the next seam has begun to cause the trimming device to again trim the thread.

6. In a buttonhole sewing machine, the combination with work-holding means, of a frame carrying a stitch-forming mechanism and movable to produce a feeding movement during the formation of the stitches around a buttonhole and also movable to carry the parts from relative stitching posi' tion to relative huttonhole-cutting position, a thread-holding device, a thread-triunning de vice, means operative only during the movement of the frame which occurs at the end of each buttonhole to cause the threadholding device to seize and hold the needle thread, and means renoered operative by the move ment of the frame from stitching to buttonhole-cutting position to cause the trimmer to operate, and also rendered operative by the feeding movement when the stitching on a buttonhole begins to again cause the trimmer to operate.

7. In a sewing machine, the combination with stitch-forming mechanism and Workholding means movable relatively to each other, of a thread holder, a thread cutter having a cutting edge, means operative at the end of a sewing operation by the relative movement of the Work-holding means and stitch-forming mechanism to cause the thread holder to grip the thread and thereafter to move the thread cutter to cause the cutting edge thereof to sever the thread,

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said means also operating the thread cutter to cause said cutting edge to cut the thread at the beginning of the seam.

I 8. 111 a sewing machine, the combination with Work-holding means and stitch-forming mechanism having a relative movement, of a thread holder, a movable thread cutter having a cutting edge, means operated by said relative movement to cause the thread holder to grip the thread at the end of the 10 In testimony whereof, I have signed my 15 name to this specification.

JOHN KIEWICZ. 

